The present invention relates to a hybrid fiber/coax (HFC) access communication network and, more particularly, to a network management system that monitors both downstream and upstream conditions and is capable of detecting and sectionalizing system faults in real time.
Modern cable systems utilize a hybrid fiber/coax (HFC) architecture in which signals are distributed via a fiber optic connection to a node that converts the optical signal to an electrical signal, then distributes the signals to residences via a tree and branch coaxial cable distribution network. The distribution network comprises network elements such as coaxial cable, amplifiers, line extenders and taps. At the subscriber side, terminal equipment supports the delivery of cable services to subscribers. Cable services have evolved from video services to data and voice services, introducing at the same time new terminal equipment. The set-top box (STB) terminal equipment supports video services which include broadcast TV and interactive services such as video-on-demand (VOD) and xe2x80x9cnearxe2x80x9d video-on-demand (NVOD).
Data and voice services are supported by cable modems and communication gateways, respectively, which also require the use of an upstream signal path. The network is provisioned as a bi-directional network by using a fiber optic return signal path from the node to the headend. A return band, typically designated at 5-42 MHz, is used to support transmissions from devices in the home (or located on the side of the home) back to the headend. Additional network elements may be placed inside the cable network to support service delivery or to monitor service quality. The cable modem is a network interface element for providing data services such as Internet access and other related services to the subscriber. A cable modem generally uses standardized communication methods based on Cable Labs"" Data Over Cable System Interface Specification (DOCSIS) to access data services through the cable network. A cable modem termination system (CMTS) located at the HFC access network head end side provides an interface to the data network, as well as an interface to the cable modems. In particular, cable modems can be identified by one or more unique addresses including, but not limited to, a Media Access Control (MAC) address or an IP address.
A television set-top box supports video and data services that may be accessed through the television interface. Set-top functionality can also be extended to support telecommunications services including voice and video telephony. In a particular embodiment, an exemplary set-top box receives analog and digital signals on the downstream through the HFC cable plant, and can use a variety of communications techniques for return path communications, including telephone plant return, response to polling from the headend, or cable modem communications, including the use of DOCSIS-compliant or other cable modem technology. Set-tops are typically identified by a unique address which can be, as mentioned above, a MAC address. Another network element which can be monitored and managed is defined as a xe2x80x9ccommunication gatewayxe2x80x9d, where the communication gateway is located at or near the subscriber residence and functions to support a variety of voice and data services. An exemplary communication gateway comprises a cable modem along with a microprocessor, digital signal processing (DSP) unit, and other hardware required to support IP telephony services. Along with its IP telephony services support feature, a communication gateway can also perform ingress monitoring operations. The communication gateway may be located outside the residence, typically on the side of the house, or can be inside the home in a central location, such as a basement or attic. Alternatively, the communication gateway functionality can be incorporated into a television set-top.
A telephony test point (TTP) is a monitoring element placed at a specific point inside the cable plant and used to perform certain operations autonomously, or under the control of a network management system. The basic functions of the TTP are to monitor and control ingress, discover the topology of the cable network, and identify the ingress sources. The TTP is based on a communication gateway, without the telephony interfaces. In one embodiment, the TTP is equipped with a tunable spectrum analyzer to monitor ingress.
Although these various components are capable of autonomous operation in an HFC access network, the impact of ingress at a particular network element can result in affecting the performance of other network elements, eventually resulting in system failures within portions of the network. The source and extent of ingress may be difficult to identify and, as a result, time-consuming to locate and remediate.
A need remains, therefore, for an overall network management system that can quickly and efficiently locate various network faults and, in general, monitor network xe2x80x9chealthxe2x80x9d and allow various service providers to interact with selected network elements to optimize the delivery of the various services to subscribers.
These and other needs remaining in the prior art are addressed by the present invention, which relates to a hybrid fiber/coax (HFC) access communication network and, more particularly, to a network management system that monitors both downstream and upstream conditions and is capable of detecting and sectionalizing system faults in real time.
In accordance with the present invention, an HFC access network manager (HAM) is disposed at the head end of an access network and is used to perform the following functions: (1) managing return path signal quality by collecting physical layer information and media access control (MAC) layer information and using the same to sectionalize faults in the network; (2) monitoring forward signal path quality through physical layer parameter measurements; and (3) using xe2x80x9ctest pointsxe2x80x9d distributed through the network to determine the presence of devices at the network endpoint terminations by. monitoring the upstream time slots (also in combination with monitoring of the downstream, known topology).
The HFC access network manager of the present invention includes, in a preferred embodiment, four separate elements that directly interact with various service providers: (1) a service provisoning element; (2) a quality of service monitoring element; (3) a diagnosis element; and (4) a network element xe2x80x9cdirect accessxe2x80x9d element. Further within the network manager of the present invention is a set of functional modules that communicate directly with various ones of the network elements to provide the desired information to the service providers, these modules including, but not limited to : (1) a downstream monitoring unit; (2) a return path monitoring unit; (3) a topology manager; (4) a terminal equipment list; and (5) a device configuration unit. Communication within the network manager of the present invention between the provider-connected elements and the network element-connected modules thus enables the management system of the present invention, in terms of both monitoring and management the various elements within the network.